Arrangement for generating extreme ultraviolet (EUV) radiation based on a gas discharge

ABSTRACT

The invention is directed to a method and an arrangement for generating extreme ultraviolet (EUV) radiation, i.e., radiation of high-energy photons in the wavelength range from 11 to 14 nm, based on a gas discharge. The object of the invention, to find a novel possibility for generating EUV radiation in which an extended life of the system is achieved with stable generation of a dense, hot plasma column, is met according to the invention in that a preionization discharge is ignited between two parallel disk-shaped flat electrodes prior to the main discharge by a surface discharge along the superficies surface of a cylindrical insulator with a plasma column generated through the gas discharge with pulsed direct voltage, which preionization discharge carries out an ionization of the working gas in the discharge chamber by means of fast charged particles. The preionization discharge is triggered within a first electrode housing and the main discharge takes place between a narrowed output of the first electrode housing and a part of the second electrode housing close to the outlet opening of the discharge chamber. The plasma develops in a part of the second electrode housing covered by a tubular insulator and, as a result of the current-induced magnetic field, contracts to form a dense, hot plasma column, one end of which is located in the vicinity of the outlet opening of the second electrode housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of German Application No. 101 51080.2, filed Oct. 10, 2001, the complete disclosure of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

[0002] a) Field of the Invention

[0003] The invention is directed to an arrangement for generatingextreme ultraviolet (EUV) radiation based on a gas discharge, i.e.,radiation of high-energy photons in the wavelength range from 11 to 14nm (EUV=extreme ultraviolet range).

[0004] b) Description of the Related Art

[0005] As structures of integrated circuits on chips become increasinglysmaller in the future, radiation of increasingly shorter wavelength willbe needed in the semiconductor industry to expose these structures.Lithography machines with excimer lasers which attain their shortestwavelength at 157 nm and in which transmission optics or catadiopticsystems are employed are currently in use.

[0006] Therefore, radiation sources which further increase resolutionwith even shorter wavelengths for imaging will have to be available inthe future (around the year 2007). However, the optical systems mustcomprise reflection optics at wavelengths below 157 nm because there areno available materials which are transparent for these wavelengths. Whenusing reflection optics, the numerical aperture is limited and thediversity of optical elements is restricted. The lower numericalaperture of the optics results in decreased resolution of the systemwhich can only be compensated by an even shorter wavelength (by about anorder of magnitude).

[0007] In principle, both laser-induced plasmas and gas dischargeplasmas are suited for generating EUV radiation. Laser-induced plasmarequires an energy conversion in two stages: from electrical energy tolaser radiation energy and from laser energy to EUV radiation energy.This twofold conversion results in reduced conversion efficiencycompared to gas discharge.

[0008] With respect to gas discharges, different concepts are pursued inplasma focus devices, capillary discharge devices, hollow cathodedischarge devices and Z-pinch devices.

[0009] Compared to the other concepts, the plasma focus method has thedisadvantage of poor spatial stability because of the formation ofplasma. In this connection, U.S. Pat. No. 5,763,930 suggests a variantusing a noble gas with lithium as working gas. However, this leads toadditional contamination of the surroundings, particularly theinsulator.

[0010] Another competing concept, capillary discharge, has only a shortlife and, consequently, limited applicability.

[0011] The Z-pinch concept exhibits good characteristics compared toother gas discharge concepts and laser-induced plasmas. In a publishedtechnical solution according to U.S. Pat. No. 5,504,795, preionizationby means of R-F (radio-frequency) discharge is realized in an insulatortube in which the plasma is likewise ignited subsequently. Thishigh-frequency preionization system is directly coupled to the dischargesystem and is therefore exposed to plasma radiation and to bombardmentby charged particles resulting in a shorter life of the insulator tubein particular.

OBJECT AND SUMMARY OF THE INVENTION

[0012] It is the primary object of the invention to find a novelpossibility for generating EUV radiation in which an extended life ofthe system is achieved with stable generation of a dense, hot plasmacolumn.

[0013] According to the invention, in an arrangement for generatingextreme ultraviolet (EUV) radiation based on a gas discharge with adischarge chamber which is enclosed by a first electrode housing and asecond electrode housing and through which a working gas flows under adetermined pressure, the two electrode housings being arranged coaxialto one another and having cylindrical superficies surfaces which facethe discharge chamber and which are isolated from one another by aninsulator layer so as to resist puncture or breakthrough, and an outletopening for the EUV radiation which is provided axially in the secondelectrode housing, the above-stated object is met in that a coaxiallyarranged preionization unit having parallel, substantially flatelectrodes at a distance from one another axially is provided in theinterior of the first electrode housing, wherein the flat electrodes aresubstantially circular and a cylindrical insulator in which at least oneelectric line is inserted is arranged between the flat electrodes, sothat a sliding discharge is generated along the superficies surface ofthe cylindrical insulator when a sufficiently high voltage is applied tothe flat electrodes, in that the first electrode housing has a narrowedoutput in the direction of the second electrode housing, and in that thecylindrical superficies surface of the second electrode housing iscovered by a tubular insulator at least in the immediate vicinity of thenarrowed output of the first electrode housing.

[0014] An end face of the first electrode housing is advantageouslyprovided as one of the flat electrodes of the preionization unit. Thepreionization unit with the cylindrical insulator is inserted into therear end face of the first electrode housing and the line for the otherflat electrode is guided into the interior of the cylindrical insulator.

[0015] The flat electrodes of the preionization unit are connected to apreionization pulse generator which advisably generates high-voltagepulses with short rise times.

[0016] The line for the other flat electrode of the preionization unitis preferably constructed as a metal tube which is provided at the sametime as a flow tube for the working gas. The tube can be used at thesame time as a leadthrough for arranging a radiation detector formeasuring the EUV radiation which is radiated back by the plasma column.

[0017] The tube of the preionization unit can advantageously communicatewith a regulated gas supply system as a gas inlet for the working gas. Avacuum system connected to the outlet opening for the EUV radiation isprovided as gas outlet.

[0018] In another construction variant, the tube of the preionizationunit is connected to a vacuum system as a gas outlet for the workinggas, wherein gas inlets communicating with a regulated gas supply systemare provided in the second electrode housing for supplying gas. The gasinlets are advisably arranged so as to be evenly distributed in a planeabout the axis of symmetry of the discharge chamber. The gas inlets canbe inserted in an end face of the second electrode housing comprisingthe outlet opening or in the cylindrical superficies surface of thesecond electrode housing. In both cases, the gas inlets are introducedradially in the discharge chamber so that the working gas flows into thesecond electrode housing as uniformly as possible.

[0019] The working gas is preferably a noble gas such as xenon, krypton,argon or neon. However, oxygen, nitrogen or lithium vapor can also beused. Also, to enhance conversion, gas mixtures of xenon or helium withadded hydrogen or deuterium can advantageously be used, or, when usinglithium vapor, helium or neon can advantageously be used as added gas.

[0020] The cylindrical insulator of the preionization unit is preferablyproduced from a material with a high dielectric constant, preferablylead zirconium titanate (PZT), lead borsilicate or lead zincborsilicate. It is advisably manufactured in such a way that it haschannels through which a coolant can flow.

[0021] In order to achieve a reliable insulation of the output of thefirst electrode housing relative to the superficies surface of thesecond electrode housing, the tubular insulator in the second electrodehousing is advantageously extended into the first electrode housing, thenarrowed output of the first electrode housing projecting into theinterior of the tubular insulator. The tubular insulator advisablycomprises a highly insulating ceramic, particularly Si₃N₄, Al₂O₃, AlZr,AlTi, BeO, SiC or sapphire.

[0022] The tubular insulator preferably completely covers thecylindrical superficies surface of the second electrode housing.

[0023] In order to generate the gas discharge (main discharge), thefirst electrode housing is advisably connected to a high-voltage pulsegenerator as cathode and the second electrode housing is preferablyconnected to a high-voltage pulse generator as anode. In anotheradvantageous construction, the first electrode housing is connected asanode and the second electrode housing is connected as cathode.

[0024] The pulse generator is advisably operated by a thyratron circuitwhich contains a single-stage or multistage compression module withmagnetically saturable cores. Alternatively, it can also be constructedexclusively from semiconductor components.

[0025] The pulse generator is advantageously adjustable to a repetitionfrequency in the range of 1 Hz to 20 kHz and to a voltage which issufficient for igniting the gas discharge and generating a plasma columnwith high density and high temperature.

[0026] Because of the high current load and thermal stress, theelectrode housings are advisably made from materials with highproportions of tungsten, tantalum or molybdenum, at least in the area ofthe outputs. Tungsten-copper alloys, particularly 90% W and 10% Cu or80% W and 20% Cu (B3C) are preferably used.

[0027] As another step for reducing wear, the electrode housings havecavities which communicate with a coolant reservoir via oppositelylocated connections. Additional cooling fins can be provided in thecavities for increasing the inner surface for heat transfer.

[0028] In a method for generating extreme ultraviolet (EUV) radiationbased on a gas discharge in which a main discharge is triggered bydirect voltage pulses in a substantially cylindrical discharge chamberwhich is enclosed by a first electrode housing and a coaxial secondelectrode housing and through which a working gas flows under a definedpressure, wherein the main discharge is supported by means ofpreionization, and a plasma column resulting from the main dischargealong the axis of symmetry of the discharge chamber emits the EUVradiation through an outlet opening of the discharge chamber, theabove-stated object according to the invention is met in general in thatprior to the main discharge a preionization discharge is ignited betweentwo parallel disk-shaped flat electrodes by means of a surface dischargealong the superficies surface of a cylindrical insulator, whichpreionization discharge, in addition to a radiation emission in thewavelength range of ultraviolet to x-ray radiation, generates fastcharged particles which cause an ionization of the working gas in thedischarge chamber, in that the preionization discharge is triggeredwithin a first electrode housing, and in that the main discharge takesplace between a narrowed output of the first electrode housing and aportion of a second electrode housing near the outlet opening of thedischarge chamber, wherein the plasma causes a progressing ionization ofthe working gas in one of the two electrode housings.

[0029] By means of the arrangement according to the invention and themethod implemented by means of this arrangement, it is possible togenerate an EUV radiation in the range of 11 to 14 nm with reproduciblegeneration of a dense, hot plasma column and an extended system life.

[0030] The invention will be described more fully in the following withreference to embodiment examples.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In the drawings:

[0032]FIG. 1 shows a schematic view of the arrangement according to theinvention;

[0033]FIG. 2 shows a construction variant of the invention with an EUVradiation outlet from the anode;

[0034]FIG. 3 shows another construction variant of the invention similarto FIG. 2, but with radiation outlet from the cathode and opposite flowdirection of the working gas;

[0035]FIG. 4 shows a voltage-time diagram of the preionization pulsegenerator and a current-time diagram of the high-voltage pulsegenerator; and

[0036]FIG. 5 shows diagrams of the discharge voltage and EUV radiation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] As is shown in FIG. 1, the basic arrangement according to theinvention comprises a first electrode housing 1 and a second electrodehousing 2 which together form a discharge chamber 3, the two electrodehousings 1 and 2 being insulated relative to one another againstbreakthrough by an insulating layer 4 and a tubular insulator 22 in theinterior of the second electrode housing 2, a preionization unit 5 whichis arranged coaxially inside the first electrode housing 1 andcommunicates with the preionization pulse generator 6, a high-voltagepulse generator 7 to which the two electrode housings 1 and 2 areconnected, a gas supply system 8 for feeding working gas into thedischarge chamber 3 so as to be regulated in a defined manner, and avacuum system 9.

[0038] The two electrode housings 1 and 2 are arranged coaxially oneover the other and have inner cylinder superficies surfaces 11 and 21which define the discharge chamber 3 radially around the axis ofsymmetry 31. The first electrode housing 1 has a narrowed output 12 inthe direction of the second electrode housing 2 and has a plane rear endface 13 at which the preionization unit 5 projects coaxially into theinterior.

[0039] At its cylindrical superficies surface 21, the second electrodehousing 2 is covered toward the discharge chamber 3 by the tubularinsulator 22 which, together with the insulation layer 4 which isarranged along the surface in lateral direction to the axis of symmetry31 of the discharge chamber 3, electrically isolates the electrodehousings 1 and 2 from one another. This prevents an electric dischargebetween the first electrode housing 1 and the adjoining parts (includingessential parts of the cylindrical superficies surface 21) of the secondelectrode housing 2, and the discharge takes place in a defined mannerin the interior of the tubular insulator 22 between the narrowed output12 of the first discharge chamber 1 and the end (not insulated) of thesecond electrode housing 2.

[0040] Because of its narrowed output 12, the first electrode housing 1has a relatively small opening toward the second electrode housing 2. Inthis way, a separate room in which preionization takes place is formedin the first electrode housing 1. The preionization unit 5 contains acylindrical insulator of highly insulating ceramic (hereinafter referredto as ceramic cylinder 51) which is guided coaxially into the interiorof the first electrode housing 1 through the rear end face 13, andcoaxial disk-shaped flat electrodes 52 which are arranged concentricallyoutside the ceramic cylinder 51 on the one hand and on its end face inthe interior of the first electrode housing 1 on the other hand. Theelectric connection of the flat electrodes 52 to a preionization pulsegenerator 6 is carried out inside the ceramic cylinder 51.

[0041] A working gas which is admitted by a regulated gas supply system8 under defined pressure flows through the discharge chamber 3, whereina vacuum (in the range of 1 to 20 Pa) is realized in the entiredischarge chamber 3 by means of an oppositely connected vacuum system 9.

[0042] When the preionization pulse generator 6 sends a sufficientvoltage pulse to the flat electrodes 52, a sliding discharge 61 formsalong the surface of the ceramic cylinder 51. In addition to radiationin the range of ultraviolet to x-ray, this sliding discharge 61generates fast charged particles resulting in a progressing ionizationof the working gas in the entire discharge chamber. The main dischargeis then ignited by means of the high-voltage pulse generator 7 via thefirst and second electrode housings 1 and 2 and leads to the formationof gas discharges and cylindrical plasma between the narrowed output 12of the first electrode housing 1 and the front side 23 of the secondelectrode housing 2. The considerable flow of current generates atangential magnetic field of a magnitude such that the plasma contractson the axis of symmetry 31 of the discharge chamber 3 so that there isformed in the second electrode housing 2 a dense, hot plasma column 71whose emitted EUV emission 72 exits through the outlet opening 32 of thedischarge chamber 3 located in the end face 23 of the second electrodehousing 2 and is focused by a first collecting optical system (notshown).

[0043] In FIG. 2, the preionization unit 5 is simplified in that one ofthe flat electrodes 52 is combined with the end face 13 of the firstelectrode housing 1. The construction of the preionization unit 5 isaccordingly simplified in that only one (central) line is required forthe flat electrode 52 remaining at the end of the ceramic cylinder 51.In this case, the latter can be a metallic tube 53 which is provided atthe same time as a gas inlet 81 for the flow of working gas through thedischarge chamber 3. The metallic tube 53 is accordingly connected tothe preionization pulse generator 6 which communicates with the firstelectrode housing 1. In this example, the first electrode housing 1functions as the cathode and the second electrode housing 2 is theanode. The electrode housings 1 and 2 are connected to the high-voltagepulse generator 7 which can supply electric pulses with repetitionfrequencies between 1 Hz and 20 kHz. For photolithographic purposes inthe semiconductor industry, repetition frequencies between 4 and 8 kHzmust be set in order to achieve sufficient exposure per surface and timeand low intensity variations.

[0044] In the example according to FIG. 2, the working gas is introducedthrough the metallic tube 53 of the preionization unit 5. The pressureof the working gas is held constant via the gas supply system 8 whichleads to an optimal gas flow in the discharge chamber 3. A preionizationpulse is applied between the first electrode housing 1 (which is alsothe cathode for the main discharge) and the flat electrode 52. For thispurpose, the disk-shaped flat electrode 52 is electrically connectedwith the preionization pulse generator 6 via the tube 53. Thepreionization pulse generator 6 generates electric pulses with a typicalrise time of 10¹¹ V/s and voltages which are sufficient for generating asurface discharge (sliding discharge 61) at the outer surface of theceramic cylinder 51. In addition to radiation from the ultraviolet tothe x-ray range, this sliding discharge 61 (at the given electrodepolarity) generates, above all, fast electrons which produce sufficientionization of the working gas of the entire discharge chamber 3. Themain discharge pulse then ignites a gas discharge between the output 12of the first electrode housing 1 and the end face 23 of the secondelectrode housing 2. The plasma forms virtually in the entire interiorspace of the tubular insulator 22. The peak current of the high-voltagepulse generator 7 is about 54 kA with a pulse duration of 330 ns. Theplasma which is initially shaped as a cylinder “implodes” due to themagnetic forces induced by the electrical current through the gasdischarge to the axis of symmetry 31 of the discharge chamber 3 formedby the electrode housings 1 and 2 and forms a plasma column 71 of highdensity (with a length from 1 mm to 50 mm and a diameter from 0.2 to 4mm) directly in front of the outlet opening 22 of the second electrodehousing 2 (anode). The high-voltage pulse generator 7 contains athyratron circuit with a single or multiple compression stage based onmagnetically saturable cores (as disclosed, e.g., in U.S. Pat. No.6,226,307 B1). However, a high-voltage pulse generator 7 containingsemiconductor components can also be used.

[0045] The main discharge takes place a few microseconds (μs) later thanthe surface discharge of the preionization unit 5. To illustrate this,the signals of the preionization voltage, the discharge current, thedischarge voltage and a photodiode signal of the EUV emission 72 areshown in FIGS. 4 and 5.

[0046] The selected type of preionization guarantees the homogeneoustriggering of the discharge by the main discharge pulse. The decisiveadvantage of this preionization is that the preionization unit 5 is notdirectly exposed to the radiation from the plasma and a long useful lifeis accordingly achieved.

[0047] The tubular insulator 22 at the inner cylindrical superficiessurface 21 of the second electrode housing 2 is made from Si₃N₄ and hasproven to be a very durable material with a life of 2×10⁶ pulses incontinuous operation without destruction. Instead of Si₃N₄, variousother insulating materials such as A1 ₂O₃, AlN, AlZr, AlTi, SiC orsapphire can also be used.

[0048] The electrode housings 1 and 2 are produced in such a way that acontinuous flow of coolant can flow around the discharge chamber 3 ineach cooling channel 14 and 24. In order to increase the transfer ofheat, cooling fins 15 and 25 are incorporated in the cooling channels 14and 24 of the first and second electrode housings 1 and 2. The coolantcan accordingly absorb heat on an enlarged surface and cooling power isimproved. The coolant is provided by coolant reservoirs 17 and 27 andsupplied to and removed from the electrode housings 1 and 2 viaoppositely located connections 16 and 26. This design is necessarybecause an EUV source for industrial applications must be operatedcontinuously for several weeks. If not cooled, the electrodes wouldreach extremely high temperatures due to the current and radiation.Cooling is also provided in the preionization unit 5 via channels 54. Inboth cases, liquids with low viscosity such as oil (e.g., Galden) ordistilled or deionized water are used as coolants.

[0049] The arrangement according to the invention can also be operatedwith reversed polarity of the high voltage. In this connection, FIG. 3shows a corresponding view in which the electrode polarity of the firstand second electrode housing 1 or 2 is changed. Compared to thepreionization unit 5 described in the preceding example, with thepolarity of the preionization voltage likewise being reversed, only thegeneration of fast charged particles is changed in such a way thatinstead of electrons only ions are released in the sliding discharge 61.However, they cause a preionization of the working gas in the dischargechamber 3 in the same way. Aside from the changed direction of thedischarge current between the first and second electrode housings 1 and2, however, the generation of the plasma, the formation of the plasmacolumn 71 and the emission of the EUV radiation 72 arc achieved in thesame manner as described in FIG. 2.

[0050] It is also important to note the modified gas feed in theembodiment form according to FIG. 3 which has gas inlets 82 in thesecond electrode housing 2 in this example. This design has theadvantage of uniform flow through the second electrode housing 2 inparticular and the main discharge is ignited homogeneously. For thispurpose, the gas inlets 82 at the second electrode housing are arrangedso as to be uniformly distributed (or are arranged symmetrically inpairs) and ensure a uniform flow of gas into the discharge chamber 3. Onthe other side of the discharge chamber 3 in the first electrode housing1, the tube 53 for the through-flow of working gas is provided in amanner analogous to the construction of the preionization unit 5according to FIG. 2 and, in this case, is connected to the vacuum system9. However, the vacuum required in the discharge chamber 3 for thedischarge processes should be supported—as indicated in FIG. 2—byanother connection of a main vacuum system 91 after the outlet opening32 of the discharge chamber 3.

[0051] Other design variants of the invention are possible withoutdeparting from the framework of the present invention. In the precedingexamples, an aspect ratio of the electrode housings 1 and 2 (diameter tolength) of approximately 1:1 was assumed, but substantially differentratios are also permissible as long as the described discharge processes(preionization and main discharge) take place in the manner describedabove. The geometric shapes of the electrode housings 1 and 2 can alsobe substantially modified with respect to their axial separation intotwo chambers, wherein the characteristics of the EUV source are changed,but without departing from the principle of the generation of areproducible stable plasma with spatially isolated preionization.

[0052] While the foregoing description and drawings represent thepresent invention, it will be obvious to those skilled in the art thatvarious changes may be made therein without departing from the truespirit and scope of the present invention.

[0053] Reference Numbers

[0054]1 first electrode housing

[0055]2 cylindrical superficies surface

[0056]12 narrowed output

[0057]13 end face

[0058]14 cooling channels

[0059]15 fins

[0060]16 connections

[0061]17 coolant reservoir

[0062]2 second electrode housing

[0063]21 cylindrical superficies surface

[0064]22 tubular insulator

[0065]23 end face

[0066]24 cooling channels

[0067]25 cooling fins

[0068]26 connections

[0069]27 coolant reservoir

[0070]3 discharge chamber

[0071]31 axis of symmetry

[0072]32 outlet opening

[0073]4 insulator layer

[0074]5 preionization unit

[0075]51 ceramic cylinder (cylindrical insulator)

[0076]52 flat electrodes

[0077]53 tube

[0078]54 channels

[0079]6 preionization pulse generator

[0080]61 sliding discharge

[0081]7 high-voltage pulse generator

[0082]71 plasma column

[0083]72 EUV radiation

[0084]8 regulated gas feed system

[0085]81 gas inlet (in the first electrode housing)

[0086]82 gas inlets (in the second electrode housing)

[0087]9 vacuum system

[0088]91 main vacuum system

What is claimed is:
 1. An arrangement for generating extreme ultraviolet(EUV) radiation based on a gas discharge comprising: a discharge chamberwhich is enclosed by a first electrode housing and a second electrodehousing and through which a working gas flows under a defined pressure;said two electrode housings being arranged coaxial to one another andhaving cylindrical superficies surfaces which face the discharge chamberand which are isolated from one another by an insulator layer so as toresist breakthrough; an outlet opening for the EUV radiation which isprovided axially in the second electrode housing; a coaxially arrangedpreionization unit having two parallel, substantially flat electrodes ata distance from one another axially being provided in the interior ofthe first electrode housing; said flat electrodes being substantiallycircular; a cylindrical insulator in which at least one electric line isinserted being arranged between said flat electrodes, so that a slidingsurface discharge is generated along the superficies surface of thecylindrical insulator when a sufficiently high voltage is applied to theflat electrodes; said first electrode housing having a narrowed outputin the direction of the second electrode housing; and said cylindricalsuperficies surface of the second electrode housing being covered by atubular insulator at least in the immediate vicinity of a narrowedoutput of the first electrode housing.
 2. The arrangement according toclaim 1, wherein an end face of the first electrode housing is providedas one of the flat electrodes of the preionization unit, wherein thepreionization unit with the cylindrical insulator is inserted into theend face of the first electrode housing and the line for the other flatelectrode is guided into the interior of the cylindrical insulator. 3.The arrangement according to claim 1, wherein the flat electrodes of thepreionization unit are connected to a preionization pulse generatorwhich generates high-voltage pulses with short rise times.
 4. Thearrangement according to claim 2, wherein the line for the other flatelectrode of the preionization unit is a metal tube which is provided atthe same time as a flow tube for the working gas.
 5. The arrangementaccording to claim 4, wherein the tube is provided at the same time as aleadthrough for arranging a radiation detector for measuring the EUVradiation which is radiated back by the plasma column.
 6. Thearrangement according to claim 4, wherein the tube of the preionizationunit communicates with a regulated gas supply system as a gas inlet forthe working gas.
 7. The arrangement according to claim 4, wherein thetube of the preionization unit is connected to a vacuum system as a gasoutlet for the working gas, wherein gas inlets communicating with aregulated gas supply system are provided in the second electrode housingfor supplying gas.
 8. The arrangement according to claim 7, wherein thegas inlets are arranged so as to be evenly distributed in a plane aboutthe axis of symmetry of the discharge chamber.
 9. The arrangementaccording to claim 8, wherein the gas inlets are arranged so as to beevenly distributed in the cylindrical superficies surface of the secondelectrode housing.
 10. The arrangement according to claim 8, wherein thegas inlets are arranged so as to be evenly distributed at an end face ofthe second electrode housing comprising the outlet opening.
 11. Thearrangement according to claim 9, wherein the gas inlets are introducedradially into the second electrode housing.
 12. The arrangementaccording to claim 4, wherein a noble gas is used as working gas. 13.The arrangement according to claim 12, wherein the working gas is xenon.14. The arrangement according to claim 4, wherein oxygen or nitrogen isused as working gas.
 15. The arrangement according to claim 4, whereinlithium vapor is used as working gas.
 16. The arrangement according toclaim 12, wherein a mixture is used as working gas and wherein the addedgas is hydrogen or deuterium.
 17. The arrangement according to claim 13,wherein a mixture is used as working gas and wherein the added gas ishelium or neon.
 18. The arrangement according to claim 1, wherein thecylindrical insulator of the preionization unit is produced from amaterial with a high dielectric constant.
 19. The arrangement accordingto claim 18, wherein the insulator is selected from a group consistingof lead zirconium titanate (PZT), lead borsilicate or lead zincborsilicate.
 20. The arrangement according to claim 1, wherein thecylindrical insulator of the preionization unit has channels for thecoolant to flow through.
 21. The arrangement according to claim 1,wherein the tubular insulator completely covers the inner cylindricalsuperficies surface of the second electrode housing.
 22. The arrangementaccording to claim 1, wherein the tubular insulator extends into thefirst electrode housing and the narrowed output of the first electrodehousing projecting into the interior of the tubular insulator.
 23. Thearrangement according to claim 1, wherein the tubular insulatorcomprises a highly insulating ceramic selected from the group consistingof Si₃N₄, Al₂O₃, AlZr, AlTi, BeO, SiC or sapphire.
 24. The arrangementaccording to claim 1, wherein the first electrode housing is connectedto a high-voltage pulse generator as cathode and the second electrodehousing is connected to a high-voltage pulse generator as anode.
 25. Thearrangement according to claim 1, wherein the first electrode housing isconnected to a high-voltage pulse generator as anode and the secondelectrode housing is connected to a high-voltage pulse generator ascathode.
 26. The arrangement according to claim 1, wherein thehigh-voltage pulse generator contains a thyratron circuit connected to asingle-stage or multistage compression module with magneticallysaturable cores.
 27. The arrangement according to claim 1, wherein thehigh-voltage pulse generator contains semiconductor components.
 28. Thearrangement according to claim 26, wherein the high-voltage pulsegenerator is adjustable to repetition frequencies in the range of 1 Hzto 20 kHz and voltages which are sufficient for igniting the gasdischarge and for compressing the plasma to a column with high densityand high temperature.
 29. The arrangement according to claim 1, whereinthe electrode housings are made from materials with high proportions oftungsten, tantalum or molybdenum, at least in the area of their surfacesheaded to the plasma.
 30. The arrangement according to claim 29, whereinthe electrode housings comprise in the area of their surfaces headed tothe plasma alloys of tungsten-copper, in particular, 90% W and 10% Cu,or 80% W and 20% Cu (B3C).
 31. The arrangement according to claim 1,wherein the electrode housings have cavities in the housing wall whichcommunicate with a coolant reservoir via oppositely located connections.32. The arrangement according to claim 31, wherein cooling fins areprovided in the cavities for increasing the inner surface for heattransfer.
 33. A method for generating extreme ultraviolet (EUV)radiation based on a gas discharge in which a main discharge isinitiated by direct voltage pulses in a substantially cylindricaldischarge chamber which is enclosed by a first electrode housing and acoaxial second electrode housing and through which a working gas flowsunder a defined pressure, wherein the main discharge is supported bypreionizations and a plasma column resulting from the main dischargealong the axis of symmetry of the discharge chamber emits the EUVradiation through an outlet opening of the discharge chamber, comprisingthe steps of: igniting, prior to the main discharge, a preionizationdischarge between two parallel circular flat electrodes by a surfacedischarge along the superficies surface of a cylindrical insulator,which preionization discharge, in addition to a radiation emission inthe wavelength range from ultraviolet to x-ray radiation, generates fastcharged particles which cause an ionization of the working gas in thedischarge chamber; wherein the preionization discharge is ignited withinthe first electrode housing; and allowing the main discharge to takeplace between a narrowed output of the first electrode housing and aportion of a second electrode housing near the outlet opening of thedischarge chamber, wherein the plasma develops in a tubular insulatorwhich shields essential parts of the second electrode housing relativeto the first electrode housing and, as a result of the current-inducedmagnetic field, the plasma contracts to form a dense, hot plasma column,one end of which is located in the vicinity of the outlet opening of thedischarge chamber.
 34. A method according to claim 33, wherein thepreionization discharge and the main discharge are triggeredsuccessively in time in a synchronized manner with a repetitionfrequency between 1 Hz and 20 kHz.
 35. An arrangement according to claim33, wherein the preionization discharge is triggered between a flatelectrode and the first electrode housing connected as cathode, and themain discharge takes place between the narrowed output of the firstelectrode housing and an open portion of the second electrode housingwhich is covered by the tubular insulator and connected as anode.
 36. Amethod according to claim 33, wherein the preionization discharge istriggered between a flat electrode and the first electrode housingconnected as anode, and the main discharge takes place between thenarrowed output of the first electrode housing and an open portion ofthe second electrode housing which is covered by the tubular insulatorand connected as cathode.